How to Fix a Garage Door Gap
A garage door gap of almost any size is an invitation to unwanted guests. Gaps along the sides and top of the door let in wind, rain and snow, and gaps along the floor let in not just weather but also critters. Mice can squeeze through a garage door gap the size of a dime. Rats need no more than the size of a quarter. And don't forget about snakes.
Of course, you might dislike gaps simply because of how they look. In any case, troubleshooting a garage door gap is much easier than eliminating gaps in things like teeth … or generations. Find out how to tackle simple DIY fixes, and when to call a pro for trickier garage door repair.
Gaps Along the Sides and Top of the Door
Inspect the stops. Garage door stops — strips of trim running along both sides and the top of the door opening — cover the gaps between the door's edges and jambs and provide a weather seal by means of a flexible flap or flange that overlaps onto the door when it's closed. If your stops aren't doing their job, they probably need to be moved (usually closer to the door) or replaced.
Check the tracks. If the garage door stops look okay but the door is out of plumb (not perfectly vertical when closed), check the vertical sections of the roller tracks on each side of the door; they should be plumb and hold the door at a consistent distance from the side stops (assuming the stops themselves are plumb). The tracks are mounted on brackets with slotted holes. Loosen the mounting bolts and nudge the tracks a bit so the door is closer to the stops (and plumb), then re-tighten the bolts. Just be careful not to go too far; the door needs some play. If in doubt, call a garage door expert.
Gaps Along the Bottom of the Door
A garage door gap where the door meets the floor can have numerous causes, which will determine your choice of solution.
Adjust the limit switches if your garage door won’t close all the way. Flexible garage door seals are easy prey for animals that have the will and need to chew. To discourage them, adjust the limit switches so that this seal is compressed between the bottom of the door and the floor. Limit switches, which control the final position of the door, are usually located up at your opener. Since there are many types of openers, read through your owners’ manual for the specifics of your particular model.
Replace the seal. The seal itself may be the culprit, due to age and normal wear and tear. DIY replacement is fairly easy. Purchase a seal replacement kit from your garage door manufacturer or found online through a reputable supplier. Installation, which varies by manufacturer, may be as simple as driving screws through preconfigured holes or more complex, requiring you to feed the garage door seals along a channel or track. If you have the sliding variety, manufacturers will often recommend a special lubricant to make the job go more smoothly.
Compensate for settling in either the garage's framing or the garage floor, or both. If the door is wood and the gap isn't severe, trim the door to follow the floor. Set a compass to match the widest part of the garage door gap, then drag the compass along the floor, using its pencil end to mark a cut line along the bottom door panel (or substitute a wood block and carpenter's pencil). Cut the door with a jigsaw (safest for beginners) or a circular saw (for advanced DIY homeowners), then sand and refinish the cut end before adding new weatherstripping.
Replace the weatherstripping. For metal doors, replace the weatherstripping to solve gapping along the floor, using one of two different types. The first is a bulb seal, sort of like a really flimsy garden hose with a T-shaped spine along its top. The spine slides into a single groove in the bottom edge of the door panel. The second is U-shaped with two top edges that slide into two channels in the door. Make sure the weatherstripping is tall enough to cover your garage door gap: for bulb-type stripping, choose the largest diameter you can find; for U-shaped, choose the widest (measured when laid out flat).
Add more concrete to the floor. It’s not uncommon for concrete garage floors to shift or drop after being poured. This can be troublesome since concrete slabs seldom move in even or parallel ways. Add a layer of concrete to provide a flat, level surface for the garage door seals to rest on.
Install a garage door threshold. Home centers and automotive retailers sell threshold kits consisting of a rubber threshold strip and glue (plus sometimes a caulking gun). Simply glue the threshold permanently to the garage floor so the door rests on it when closed. ADVANTAGE: eliminates a garage door gap and keeps water from flowing in if your driveway slopes toward the garage. DISADVANTAGE: creates a slight barrier against sweeping or hosing stuff out of the garage.
Call a pro. Call a professional for garage door adjustment if the door is out of level -- or for replacement if the bottom panel is sagging.
This article was updated November 29, 2017.